1. She apologized for ______ to attend the meeting.

       A. her being not able                                        B. her to be not able  

       C. her not to be able                                         D. her not being able

2. ______ you were busy, I wouldn’t have bothered you with my questions.

       A. If I realized                                                        B. had I realized

       C. Did I have realized that                                 D. As I realized

3. There are many kinds of metals, ______.

       A. each having its special properties                   B. having its special properties

       C. one has its special properties                          D. each has its special properties

 答案及解析：

1.     D。此為固定語序，sb’s not doing sth. 

2.     B。典型的表示與過去事實相反的虛擬語氣句型，條件狀語從句用if+主語+過去分詞，主句用：主語+ would (not)/should（not）+過去分詞，當省略if 時，條件從句中的had 提前。

3.     A。本句考察獨立主格結構。B沒有主語；逗號不能連接兩個獨立完整的句子，因此排除C，D；只能選A。句意為“金屬有很多種，每一種都有它的特性�！�